Get is a very busy verb in English.
It's mostly an auxiliary verb, and it almost always is Inchoative in meaning -- i.e, it refers to a change of state, by referring to a state that is beginning.
Inchoative predicates (verbs and adjectives) often occur in sets of Stative, Inchoative, and Causative, which are often the same word, but sometimes not:
- Stative predicate:
The gate is open (wide)/(wide) open.
The gate is closed (tight).
The dog is dead.
The dog is tired (out).
He is (located) at X.
They have (= possess) the book.
- Inchoative predicate:
The gate opened (wide).
The gate closed (tight).
The dog died.
The dog tired. ~ The dog got tired (out).
He came/went to X.
They got (= received) the book.
- Causative predicate:
We opened the gate (wide).
We closed the gate (tight).
We killed the dog.
We tired the dog (out).
We brought/took him to X.
They got (= acquired) the book.
Get is so busy because it's the inchoative of both the auxiliary verb be and the auxiliary verb have. And these auxiliary verbs participate in an awful lot of constructions. Therefore, so does get.
- Some examples of Inchoative uses of get (many idiomatic):
- He was tired. ~ He got tired. (get = 'come to be')
- He is moving. ~ He got moving.
- He is married. ~ He got married.
- He is being married. ~ He is getting married.
- He is tired. ~ He got tired.
- He has a cold. ~ He got a cold. (get = 'come to have')
- He had it done. ~ He got it done.
- He has the job. ~ He got the job.
- He has to retire. ~ He has got to retire ~ He's gotta retire.
Distributional refers to the distribution of words in utterances. Where they go, where they don't.
Different types of word is what syntactic categories means. You may have learned the concept as "parts of speech". The list you give is different from the list in the article, so let's ignore that.
The point is that whether a word is called a noun or a complementizer or a preposition depends not on what it means (that's semantic, i.e, meaning), but on how it's used (that's syntactic, i.e, grammar). For instance, rock is a noun in the first sentence below, but a verb in the second:
- An earthquake could shift the rock down the hill.
- An earthquake could rock the stone down the hill.
Very few words in English are intrinsically only one part of speech, and those that are are mostly function words like the and not, which are part of the machinery of grammar, and don't really have lexical meanings like rock or shift.
Definitions of noun like 'person, place, or thing' are not distributional, but semantic, because they refer to what a noun can mean. And semantic definitions of grammatical terms are unsatisfactory; they don't work -- truth and liberty are clearly nouns, but are they people, places, or things?
Distributionally, if a word in English can be modified by an article, for instance, it's a noun;
if it can be put in the past tense, it's a verb. And so on. There are tests you can make.
That's all, really.
Best Answer
The ‘Cambridge Grammar of English’ by Carter and McCarthy calls this construction the get-passive. That perhaps becomes clearer if we re-write the sentence as They will be married in April. Married is the past participle of the verb marry, just as it is in the more conventional passive. As the authors say, 'the get-passive is used in more informal contexts and is more common in spoken than in written English.’